Digital video distribution systems are designed to deliver large numbers of program channels from a central location to the televisions, computers or set top boxes of remote viewers. The number of available channels has increased dramatically in recent years, as more sophisticated distribution systems have come into widespread use. A typical system provides a viewer with as many as one hundred or more channels to select from at any given time. This can create a serious inconvenience for a viewer who is attempting to find a program of interest. Simply sequencing through all available channels, although an acceptable approach for systems with a limited number of channels, has become increasingly tedious and time-consuming as the number of available channels has proliferated.
The current method of selecting and identifying program channels in most systems remains tightly coupled to the carrier frequency on which the channel is sent. Furthermore, each frequency generally supports only a single channel. Broadcasts in the Very High Frequency (VHF) band, for example, utilize 8 MHz channels which are sequentially numbered 1, 2, 3 . . . etc. During the fifty years that these channels have been used for television broadcasts, the station operators have invested a great deal of money and effort to build a brand identity for their station based on the channel number that the station operates on. Naturally, broadcasters will want to maintain their channel identity even after a switch to a new digital television standard. The advent in the United States of the Advanced Television Standard based on digital video distribution brings a number of complications to current channel selection techniques. First, the band used for digital television will be the UHF band with channel numbers 30 through 60. Second, each digital broadcast channel can support a single high definition television (HDTV) channel or multiple standard definition broadcast channels. Mapping the VHF channel number to the higher UHF channel number involves only a standard look-up table, and can therefore be easily implemented. A significant problem arises, however, when the digital broadcast channel includes a multiplex of several channels instead of a single HDTV channel. A further complication is the fact that the makeup of service on a given channel will generally vary as a function of time during normal operation. Currently available techniques will not permit viewers to access these channels in a straightforward and convenient manner, and will not allow broadcasters to maintain a channel identity while keeping their multiplexed channel offerings grouped together.
In a one-dimensional channel navigation technique proposed by General Instrument (GI) to the Advanced Television Standard Committee (ATSC), when a given “anchor” channel contains a multiplex of several channels, the “extra” or multiplex channels will be mapped to a linear sequence of numbers above the range currently utilized for other anchor channels. For example, if the FOX network operated channel 5 as a multiplex of several channels, channel 5 would be an anchor channel accessed in the conventional manner, but the remaining multiplex channels would be mapped to a linear sequence of much higher numbers beyond the range of the frequency-based anchor channel numbers.
The problem with this one-dimensional linear mapping technique is that preserving the groupings of channels that originate from the same broadcast providers will produce a confusing channel change scenario. Consider as an example the existing channel structure in the Washington, D.C. area, in which channel 4 is NBC, channel 5 is FOX, channel 7 is ABC and channel 9 is CBS. Assume for the moment that channels 4 and 5 are transmitting a single HDTV broadcast, and that ABC is transmitting a multiplex of four standard definition TV broadcasts. In accordance with the GI proposal, is a user were on NBC channel 4, and pressed the channel up key on his or her remote control, the user would move to FOX channel 5. Pressing the channel up key again would move the user to channel 7, the anchor ABC channel. Pressing the channel up key again moves the user to, for example, channel 101, which is the higher “virtual” channel to which the second channel of the ABC multiplex was mapped. Another press of the channel up key would bring the user to channel 102, followed by channel 103, the last channel of the four-channel ABC multiplex. Upon the next channel up command, the user moves from the ABC multiplex to CBS channel 9. In summary, the above-described series of channel up commands would yield the following sequence of channel presentations: 4571011021039. Such a sequence, in which the channel numbers can jump from high to low and back again, is likely to be confusing for many users. These and other one-dimensional techniques are unable to provide convenient user channel navigation while preserving channel branding for multiplex channels from the same provider.
It is therefore an object of the present invention to provide a channel navigation technique that preserves the existing branding investment broadcast providers have made in channel numbers, while also preserving the current user concept of channel numbers and providing efficient access to multiplexed channels originating from a common broadcast provider.